The invention is directed to a video camera fashioned as a handpiece for observing subjects in the mouth of a patient.
Given employment of a video camera as disclosed, for example, by U.S. Pat. No. 4,727,416 or U.S. Pat. No. 5,049,070, the information about the subject position and viewing direction is naturally lacking a priori at the picture screen. The subject always appears at the same location with the same alignment on the picture screen.
EP-0 389 453 discloses an endoscope proposed for dental employment, whereby the image is picked up via a fiberoptics and is supplied to a telecamera. The telecamera is arranged externally from the hand instrument and forwards the image information acquired thereat to a monitor. The end piece of the hand instrument introducible into the patient's mouth can be turned or bent relative to the fiberoptics around the longitudinal axis thereof. It is thus possible to reproduce the images erect on the monitor without the connecting cable together with the fiberoptics having to be turned for this purpose between handpiece and camera. The subject appears on the monitor at the same location having the same alignment on the picture screen, i.e. a tooth in the left half of the lower jaw likewise appears on the left side on the monitor but mirror-inverted. The same is true of the upper jaw. The dentist thus sees the image on the monitor in the same way that he would see it with a small mirror with which he observes the subject in the patient's mouth.
The same is also true of the endoscoping system disclosed by U.S. Pat. No. 4,890,159 which comprises a plurality of differently fashioned endoscopes that can be alternatively connected to a central image processing unit. The electronics of the image processing unit is constructed such that an erect or mirror-inverted video image can be reproduced at the monitor regardless of whether an endoscope having frontal or lateral image acquisition optics or an endoscope having long or short image transducer is connected to the input of the image processing unit.
U.S. Pat. No. 4,858,001 discloses that the endpiece of the hand instrument be fashioned rotatable relative to the remaining optics in order to thus be able to display the subject on the picture screen turned relative to the observer. Although such an arrangement makes it possible to correctly reproduce the side position, it does not make it possible to reproduce the position distal/proximal in a realistic fashion given a change from lower jaw to upper jaw or vestibular to lingual.
The same is true given employment of a calculating program known from the technical literature R. T. Martinez, "Image Rotation", IBM Technical Disclosure Bulletin vol. 27, no. 1B, June 1984, pp. 510/511), wherein it is proposed that the image raster be electronically turned in an electronic way with the assistance of a computer program.
U.S. Pat. No. 3,976,982 discloses an apparatus that makes it possible to manipulate images in an electronic way, in that the images that are represented in the form of two-dimensional arrays are supplied to an electronics wherein the images can be turned or mirrored in an electronic way.
Such observations may be acceptable for simple inspections. When, however, an instrument is to be guided given indirect treatment upon observation of the picture screen, it is difficult for the user to implement work in the patient's mouth with the camera and looking exclusively at the monitor. Alternate work when looking at the monitor and at the camera would mean constant readjustment.